Scottish actor/comedian Billy Connolly is convinced he should have done more to help troubled comic Robin Williams.

The Mrs. Brown star had been friends with Williams for more than a decade and was devastated when he heard his pal had taken his own life last month (Aug14) following a long battle with depression.

Connolly admits he empathised with the Mrs. Doubtfire star's problems and wishes he had stepped in to help him.

He tells Britain's Daily Mail newspaper, "I used to be not quite like Robin Williams, but I'd find it hard to switch off. Robin was 'on' all the time. He was a joy to be around, let me tell you. In all the years I knew him I never got tired of him. He was a one-off, so warm, so human.

"In my quieter moments I do sometimes think I could have done more (to help him). It's a lonely life, showbusiness. You spend a lot of time on your own, and if you dwell on these things you can hurt yourself, as Robin proved."

Connolly was diagnosed with Parkinson's disease last year (13) and it recently emerged that Williams had also been diagnosed with the early stages of the degenerative disorder prior to his death.